1028.继续畅通工程

#include<iostream>
#include<algorithm>
using namespace std;

int tree[101];

int findroot(int x){
    if(tree[x]==-1) return x;
    else {
        int temp=findroot(tree[x]);
        tree[x]=temp;
        return temp;
    } 
}

struct edge{
    int a,b,cost,flag;
    bool operator < (const edge &A) const{
       return cost<A.cost;
    }
}edge[6000];

int main(){
    int n;
    while(cin>>n){
        if(n==0) break;
        for(int i=1;i<=n*(n-1)/2;i++){
            cin>>edge[i].a>>edge[i].b>>edge[i].cost>>edge[i].flag;
            if(edge[i].flag==1) edge[i].cost=0;
        }
        for(int i=1;i<=n;i++){
                 tree[i]=-1;
        }
        int ans=0;
        sort(edge+1,edge+1+n*(n-1)/2);
        for(int i=1;i<=n*(n-1)/2;i++){
            int a=findroot(edge[i].a);
            int b=findroot(edge[i].b);
            if(a!=b){
                tree[a]=b;
                ans+=edge[i].cost;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}